U.S. patent application number 11/856364 was filed with the patent office on 2008-08-28 for cleaning liquid and nozzle plate cleaning method.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. Invention is credited to Naoaki SAKURAI, Junsei YAMABE.
Application Number | 20080207478 11/856364 |
Document ID | / |
Family ID | 39346501 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080207478 |
Kind Code |
A1 |
SAKURAI; Naoaki ; et
al. |
August 28, 2008 |
CLEANING LIQUID AND NOZZLE PLATE CLEANING METHOD
Abstract
A weakly alkali cleaning liquid suitable for use in the case of
cleaning and removing inks adhered to a nozzle plate, in an ink jet
printer using inks in which inorganic pigments and metal oxides are
mixed into polymers, is provided. In the cleaning liquid,
carbonates are added to the weakly alkali solution of pH 8 to pH
12.
Inventors: |
SAKURAI; Naoaki;
(Yokohama-shi, JP) ; YAMABE; Junsei;
(Yokohama-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Kabushiki Kaisha Toshiba
Tokyo
JP
|
Family ID: |
39346501 |
Appl. No.: |
11/856364 |
Filed: |
September 17, 2007 |
Current U.S.
Class: |
510/405 |
Current CPC
Class: |
C11D 11/0047 20130101;
C11D 7/12 20130101; B41J 2/16552 20130101 |
Class at
Publication: |
510/405 |
International
Class: |
C11D 17/00 20060101
C11D017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 21, 2006 |
JP |
2006-255512 |
Claims
1. A cleaning liquid, characterized by having carbonates added to a
weakly alkali solution of pH 8 to pH 12.
2. A nozzle plate cleaning method, characterized by having:
cleaning a nozzle plate adhered with inks in which at least one of
inorganic pigments and metal oxides is mixed into polymers, by
using a polymer dissolving solution; and cleaning the nozzle plate
by using a weakly alkali cleaning liquid of pH 8 to pH 12, after a
cleaning by using the polymer dissolving solution is carried
out.
3. The nozzle plate cleaning method of claim 2, characterized in
that carbonates are added to the weakly alkali cleaning liquid.
Description
CROSS-REFERENCE TO RELATED APPLICATION AND INCORPORATION BY
REFERENCE
[0001] This application claims benefit of priority under 35 USC 119
based on Japanese Patent Application P2006-255512, filed Sep. 21,
2006, the entire contents of which are incorporated by reference
herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a cleaning liquid and a
nozzle plate cleaning method, and more particularly, to a cleaning
method of cleaning a nozzle plate of an ink jet head and a cleaning
liquid suitable for this cleaning of a nozzle plate.
[0004] 2. Description of the Related Art
[0005] As described in Japanese Patent Application Laid Open No.
2005-145054, on an ink jet head of an ink jet printer, a nozzle
plate on which a plurality of nozzles are formed is provided. In
such an ink jet printer, the printing is carried out by adhering
ink drops injected from nozzles of the nozzle plate onto a
recording medium. When the ink drops are injected from the nozzles,
a part of the inks will be adhered to a surface of the nozzle
plate, so that there is a need to clean the surface of the nozzle
plate regularly in order to remove the adhered inks.
[0006] In the ink jet printer described in Japanese Patent
Application Laid Open No. 2005-145054, a wiping member is set in
contact with the surface of the nozzle plate and the adhered inks
are wiped off by moving this wiping member along the surface of the
nozzle plate.
[0007] The ink jet printer described in Japanese Patent Application
Laid Open No. 2005-145054 is a device for consumer use, which
mainly uses papers as the recording medium. For this reason, the
inks to be used are formed by components such that the permeability
with respect to papers is given a high importance and they can be
wiped off easily when they are adhered to metals or resins
constituting the nozzle plate. Consequently, as described in
Japanese Patent Application Laid Open No. 2005-145054, the adhered
inks can be wiped off by moving the wiping member in contact with
the surface of the nozzle plate, along the surface of the nozzle
plate.
[0008] However, in the nozzle plate cleaning method described in
Japanese Patent Application Laid Open No. 2005-145054, the
following points are not taken into consideration.
[0009] In the ink jet printer for industrial use, glasses or resins
will be used as the recording medium, and the inks to be used have
the good adhesive property with respect to glasses and resins. For
example, the inks in which inorganic pigments or metal oxides are
mixed into polymers will be used. For this reason, there has been a
problem that it is difficult to remove such inks when they are
adhered to the nozzle plate. In particular, when it is attempted to
wipe off these inks adhered to the nozzle plate by using a wiping
member, an ink-proof film made of fluorocarbon resin that is
coating on the surface of the ink plate in order to suppress the
adhering of the inks to the nozzle plate will be worn. This is
presumably caused as the inorganic pigments or metal oxides
contained in the inks will function similarly as abrasives.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to provide a
cleaning liquid to be used in cleaning inks adhered to a nozzle
plate, and a nozzle plate cleaning method using this cleaning
liquid.
[0011] The first feature according to the embodiments of the
present invention is that, in the cleaning liquid, carbonates are
added to the weakly alkali solution of pH 8 to pH 12.
[0012] The second feature according to the embodiments of the
present invention is that the nozzle plate cleaning method has
cleaning a nozzle plate adhered with inks in which at least one of
inorganic pigments and metal oxides is mixed into polymers, by
using a polymer dissolving solution, and cleaning the nozzle plate
by using a weakly alkali cleaning liquid of pH 8 to pH 12, after a
cleaning by using the polymer dissolving solution is carried
out.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a perspective view showing a schematic
configuration of an ink jet printer of one embodiment of the
present invention.
[0014] FIG. 2 is a cross sectional view showing an ink jet head
provided in the ink jet printer shown in FIG. 1.
[0015] FIG. 3 is a flow chart showing a nozzle plate cleaning
procedure.
[0016] FIG. 4 is a graph showing a measurement result of the pH
value change in time for the weakly alkali cleaning liquid with
added carbonates and the weakly alkali cleaning liquid without
added carbonates.
DETAILED DESCRIPTION OF THE INVENTION
[0017] In the following, one embodiment of the present invention
will be described with references to the drawings.
[0018] An ink jet printer 1 shown in FIG. 1 is an ink jet printer
for industrial use which uses inks in which at least one of
inorganic pigments and metal oxides is mixed into polymers, and
which has a base 2, a support body 3, a moving mechanism 4, and a
cleaning unit 5. The supporting body 3, the moving mechanism 4 and
the cleaning unit 5 are arranged on the base 2.
[0019] The support body 3 is formed in a gate shape having a
horizontal axis 3a and a pair of leg portions 3b provided at both
ends of the horizontal axis 3a, and arranged at a position
straddling across the moving mechanism 4. To the support body 3, a
movable member 6 is attached, and an ink jet head 7 is attached to
this movable member 6. The movable member 6 is attached to be
capable of ascending/descending in the Z-axis direction (vertical
direction) and capable of moving in the X-axis direction
(horizontal direction) along the horizontal axis 3a of the support
body 3.
[0020] The moving mechanism 4 has a Y-axis direction guiding plate
8, a Y-axis direction moving table 9, an X-axis direction moving
table 10, and a substrate holding table 11.
[0021] The Y-axis direction guiding plate 8 is fixed on an upper
face of the base 2. On an upper face of the Y-axis direction
guiding plate 8, a guiding groove 8a extending in the Y-axis
direction is formed.
[0022] The Y-axis direction moving table 9 is arranged on the
Y-axis direction guiding plate 8, and on a lower face of the Y-axis
direction moving table 9, a protruded portion (not shown) to be
slidably engaged with the guiding groove 8a is formed. The Y-axis
direction moving table 9 is made to be capable of sliding in the
Y-axis direction along the guiding groove 8a, by a feed mechanism
(not shown) using a feed screw and a driving motor. On an upper
face of the Y-axis direction moving table 9, a guiding groove 9a
extending in the X-axis direction is formed.
[0023] The X-axis direction moving table 10 is arranged on the
Y-axis direction moving table 9, and on a lower face of the X-axis
direction moving table 10, a protruded portion (not shown) to be
slidably engaged with the guiding groove 9a is formed. The X-axis
direction moving table 10 is made to be capable of sliding in the
X-axis direction along the guiding groove 9a, by a feed mechanism
(not shown) using a feed screw and a driving motor.
[0024] The substrate holding table 11 is fixed on an upper face of
the X-axis direction moving table 10. On an upper face of the
substrate holding table 11, a substrate 12 to be coated with inks
is mounted to be capable of being loaded/unloaded. The substrate 12
mounted on an upper face of the substrate holding table 11 is
adsorbed by an adsorption mechanism (not shown) provided on the
substrate holding table 11, and held at a fixed position. Note that
the substrate holding table 11 is made to be capable of moving in
the Y-axis direction on the Y-axis direction guiding plate 8, along
with the X-axis direction moving table 10 and the Y-axis direction
moving table 9. The substrate holding table 11 moving in the Y-axis
direction is made to be capable of moving to a position at which
the substrate 12 mounted on the substrate holding table 11 is
located below the ink jet head 7 and the coating of the ink drops
can be carried out (a position shown in FIG. 1), and a position at
which the substrate holding table 11 is off a position below the
ink jet head 7 and the loading/unloading of the substrate 12 on the
substrate holding table 11 can be carried out.
[0025] The cleaning unit 5 is a portion for cleaning the nozzle
plate to be described below which constitutes a part of the ink jet
head 7. The cleaning unit 5 has a cleaning tank 5a into which a
cleaning liquid is poured, a mechanism (not shown) for pouring the
cleaning liquid into or out of the cleaning tank 5a, and an
ultrasonic vibrator device (not shown) for applying ultrasonic
vibrations with respect to the cleaning liquid in the cleaning tank
5a.
[0026] As shown in FIG. 2, the ink jet head 7 has a plurality of
ink chambers 13, a diaphragm 14, a plurality of piezoelectric
elements 15, and a nozzle plate 16. To the ink chambers 13, the
inks in which at least one of inorganic pigments and metal oxides
is mixed into polymers are supplied from ink tanks (not shown). The
diaphragm 14 constitutes a part of a wall of each ink chamber 13. A
plurality of piezoelectric elements 15 are provided at positions to
make contact with the diaphragm 14 in correspondence to the
respective ink chambers 13. The nozzle plate 16 constitutes a part
of a wall of each ink chamber 13. On the nozzle plate 16, a
plurality of nozzles 17 connected to the respective ink chambers 13
are formed.
[0027] At the ink jet head 7, as voltages are applied to the
piezoelectric elements 15, the piezoelectric elements 15 are
deformed in contracting direction, and the diaphragm 14 is bent in
a direction for enlarging the volumes of the ink chambers 13 due to
this deformation. The inks will be poured into the ink chambers 13
with the enlarged volumes such that the amounts of inks
accommodated in the ink chambers 13 will be increased. After that,
as the application of voltages is interrupted, the contracted
piezoelectric elements 15 are recovered and the volumes of the ink
chambers 13 are recovered while a part of inks in the ink chambers
13 are injected as ink drops E from the nozzles 17. The ink drops E
injected from the nozzles 17 are coated onto a target position on
the substrate 12.
[0028] As the injection of the ink drops E from the nozzles 17 is
repeated, the inks will be adhered to portions surrounding the
nozzles 17 on the surface of the nozzle plate 16. The cleaning of
the inks adhered to the surface of the nozzle plate 16 is carried
out at the cleaning unit 5. In the case of cleaning the ink jet
head 7 at the cleaning unit 5, the ink jet head 7 is moved above
the cleaning unit 5 along the horizontal axis 3a of the support
body 3 along with the movable member 6. Then, the ink jet head 7 is
lowered to be positioned inside the cleaning tank 5a, and the
cleaning by the polymer dissolving solution and the cleaning by the
weakly alkali solution are carried out in the cleaning tank 5a in
two stages.
[0029] Note that this cleaning operation may be carried out
automatically according to a program, or may be carried out by
switch operations by an operator. In the case of carrying it out
according to a program, it may be carried out after one day's work
is finished, or it may be carried out according to a detection
result of a sensor for detecting a stained state of the nozzle
plate 16, for example.
[0030] FIG. 3 shows a procedure of an operation for cleaning the
nozzle plate 16. The operation for cleaning the nozzle plate 16 is
carried out in two stages, and the cleaning by the polymer
dissolving solution is carried out first. For the polymer
dissolving solution, a solution in which PGMEA (Polyethylene Glycol
Monomethyl Ether Acetate) and CHN (Cyclohexane) are mixed can be
used. The mixing ratio of PGMEA and CHN can be set as 1:1 weight
ratio, for example. CHN has a function for dissolving the polymers
that constitute the inks, and PGMEA has a function for penetrating
into gaps between the polymers. The polymer dissolving solution in
which PGMEA and CHN are mixed is poured into the cleaning tank 5a,
the nozzle plate 16 of the ink jet head 7 is dipped into this
polymer dissolving solution, and the ultrasonic cleaning is carried
out a preset period of time (three minutes, for example).
[0031] By carrying out the cleaning by the polymer dissolving
solution (ultrasonic cleaning), the polymers that constitute the
inks are dissolved, and the surface of the nozzle plate 16 is set
in a state in which inorganic pigments and metal oxides that
constitute the inks are remaining thereon.
[0032] Next, the polymer dissolving solution is drained from the
cleaning tank 5a, and the weakly alkali cleaning liquid of pH 8 to
pH 12 is poured into the cleaning tank 5a, and the ultrasonic
cleaning is carried out for a preset period of time (three minutes,
for example). By carrying out this cleaning using the weakly alkali
cleaning liquid (ultrasonic cleaning), the inorganic pigments, the
metal oxides and the other dusts remaining on the nozzle plate 16
are removed. The weakly alkali cleaning liquid can remove the
inorganic pigments and the metal oxides without damaging the
ink-proof film made of fluorocarbon resin that is coating the
surface of the nozzle plate 16.
[0033] By carrying out the cleaning of the nozzle plate 16 with
adhered inks in two stages of the cleaning by the polymer
dissolving solution and the cleaning by the weakly alkali cleaning
liquid, the inks formed by mixing the inorganic pigments and the
metal oxides into the polymers which has a good adhesiveness with
respect to glasses and resins can be removed surely from the nozzle
plate 16. In addition, the inks can be removed without damaging the
ink-proof film made of fluorocarbon resin that is coating the
surface of the nozzle plate 16.
[0034] The weakly alkali cleaning liquid to be used in the second
stage of the cleaning operation is formed by adding 5 ppm to 1% of
carbonates to the weakly alkali solution of pH 8 to pH 12. For
example, it is formed by adding 200 ppm of TMAH (Tri Methyl
Ammonium Hydride) carbonates to TMAH solution of pH 11. The weakly
alkali solution is prone to have its pH value lowered by absorbing
the carbon dioxide in the air. However, by adding the carbonates,
it becomes harder for the pH value to vary due to the buffer
effect, so that it becomes possible to maintain the pH value
suitable for the cleaning liquid.
[0035] Consequently, by using the cleaning liquid to which the
carbonates are added as the weakly alkali cleaning liquid, the pH
value of this cleaning liquid can be maintained in a state of being
weakly alkali over a long period of time. As a result, it becomes
possible to prevent the pH value of the weakly alkali cleaning
liquid from changing towards the neutral side in conjunction with
the elapse of time, and it becomes possible to maintain the
cleaning performance of this cleaning liquid over a long period of
time. Note that the amount of carbonates to be added can be changed
depending on a period of time for which the weakly alkali pH value
of the cleaning liquid is desired to be maintained, such that the
amount of carbonates are increased more when the period of time for
which the pH value is desired to be maintained becomes longer.
[0036] FIG. 4 is a graph showing a result of measuring the
variation of the pH value for the weakly alkali cleaning liquid of
pH 11 with added carbonates, and for the weakly alkali cleaning
liquid of pH 11 without added carbonates. In the case of not adding
the carbonates, it is demonstrated that the pH value becomes below
8 and the function of the cleaning liquid is lost after about 20
days since the measurement is started. In contrast, in the case of
adding the carbonates, it is demonstrated that the pH value is
maintained above 8 and the function of the cleaning liquid is
retained even after 60 days elapsed since the measurement is
started.
[0037] As a result, by using the weakly alkali cleaning liquid with
added carbonates in the cleaning of the nozzle plate 16, it becomes
possible to extend the period of time for which the weakly alkali
cleaning liquid can function as the cleaning liquid. Then, it is
possible to prevent an occurrence of a situation in which the
cleaning of the nozzle plate 16 becomes insufficient as the pH
value of the weakly alkali cleaning liquid is lowered by the change
in time.
[0038] Note that this embodiment is directed to an exemplary case
of using the weakly alkali cleaning liquid with added carbonates
for the purpose of cleaning of the nozzle plate 16, but the use of
this cleaning liquid is not limited to the cleaning of the nozzle
plate 16.
* * * * *